[Arrowhead1952]

Both the sewage treatment plants in Utah Valley, where I live, make incredible compost out of the sterilized sludge, mixed with chopped up green waste.

You may want to rethink that idea. I've heard some medicines don't compost completely and people flush leftovers which go into the sewage.

[Nepeta]

You may want to rethink that idea. I've heard some medicines don't compost completely and people flush leftovers which go into the sewage.

Some will, some won't depending upon the stability of the molecules. Either way, you are watering with dilute --very dilute-- solutions of such when you use tap water. At some point, you cannot agonize over all the possibilities.